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<h3>Redox potential and &#147;pe&#148;</h3>

<p><b>pe</b> = <nobr>&#8722;log{e<sup>&#8722;</sup>},</nobr> where <nobr>{e<sup>&#8722;</sup>}</nobr> 
is the &#147;activity&#148; of electrons.
This variable is used because of its similarity with pH.
But <nobr>&#147;e<sup>&#8722;</sup>&#148;</nobr> is <i>not</i> an aqueous species,
in contrast to <nobr>H<sup>+</sup>.</nobr>
The &#147;activity of electrons&#148; may be interpreted to represent the relative
tendency for a given dissolved oxidant to accept electrons,
or for electrons to &#147;leave&#148; the electrode in a galvanic cell.</p>

<p><b>pe</b> is related to the <b>redox potential, <nobr><i>E</i><sub>SHE</sub>:</b></nobr>
<table cellspacing="0" cellpadding="0" border="0"><tr><td><tt>&nbsp;&nbsp;</tt></td><td>
pe = <nobr><i>E</i><sub>SHE</sub></nobr> <i>F</i> / <nobr>(<i>R T</i> ln(10))</nobr>
</td></tr></table>
where <a href="1_Some_Constants.htm"><i>F</i></a> and
<a href="1_Some_Constants.htm"><i>R</i></a> are the Faraday and gas constants,
and <i>T</i> is the temperature in degrees Kelvin <nobr>(2.303 <i>R T</i></nobr>
/ <i>F</i> = 0.059&nbsp;V at <nobr>25&deg;C).</nobr></p>

<p><nobr><b><i>E</i><sub>SHE</sub></b></nobr>
is the potential that a platinum electrode would ideally have in contact with
the aqueous solution when measured against a <a href="ChEq_Redox_React.htm">standard hydrogen electrode</a> (SHE).
Sometimes it is referred as <b>Eh</b> (instead of <nobr><i>E</i><sub>SHE</sub>).</nobr></p>

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